Combined heat and power system

ABSTRACT

A combined heat and power system comprising an electric power generator configured to receive gaseous fuel and output electricity at a voltage level to an electrical grid and hot exhaust, a heat exchanger comprising a water input line, a water output line and a heat exchanger coil connecting the water input line and the water output line, wherein the heat exchanger coil is thermally adapted to the hot exhaust and a blower configured for selectively drawing ambient air to be mixed with the hot exhaust, whereby when hot water is demanded, the blower is not enabled and when hot water is not demanded, the blower is turned on to draw ambient air that is mixed with the hot exhaust such that the temperature of the hot exhaust can be reduced.

PRIORITY CLAIM AND RELATED APPLICATIONS

This non-provisional application claims the benefit of priority fromprovisional application U.S. Ser. No. 62/090,405 filed Dec. 11, 2014.Said application is incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention is directed generally to a combined heat and powersystem. More specifically, the present invention is directed to acombined heat and power system where the electric power generated in thecombined heat and power system is configured to be supplied via amunicipal or public electrical grid to customers of a local network.

2. Background Art

Most combined heat and power systems have been configured to receive anduse gaseous fuel to generate heat and electric power. The generatedelectric power is used locally to power devices connected within a homeor building and not any devices located at a distance on anotherlocation on a municipal or public electrical grid. The generated powermust be used immediately at the locale within which the combined heatand power system is located without the benefit of storage for later useat the locale or another locale. Therefore, the amount of electric powergenerated is typically small, e.g., sufficient only for one or tworesidences and the cost for generating power becomes prohibitively highas the equipment is incapable in providing economy of scale.

Thus, there is a need for a combined heat and power system having ameans for sharing its generated power with its neighbors or otherwiseconsumed or stored economically and thus capable of lowering the costper unit electric power generated due to economy of scale.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a combinedheat and power system including:

-   (a) an electric power generator configured to receive gaseous fuel    and output hot exhaust and electricity at a voltage level;-   (b) at least one heat exchanger including a fluid input line, a    fluid output line and a heat exchanger coil connecting the fluid    input line and the fluid output line and adapted to prepare a hot    fluid, wherein the at least one heat exchanger is thermally adapted    to the hot exhaust; and-   (c) a blower configured for selectively drawing ambient air to be    mixed with the hot exhaust, whereby when the hot fluid is demanded,    the blower is not enabled and a fluid is drawn through the fluid    input line and delivered at the fluid output line to cause heat    recovery from the hot exhaust to the fluid and when the hot fluid is    not demanded, the blower is turned on to draw ambient air that is    mixed with the hot exhaust such that the temperature of the hot    exhaust can be reduced.

In one embodiment, the fluid is water.

In one embodiment, the voltage level is disposed at a level of fromabout 5 V to about 30 V higher than the supply voltage of a publicelectrical grid such that electricity generated of the electric powergenerator may be transmitted via the public electrical grid.

In one embodiment, the electric power generator is a micro turbine. Inanother embodiment, the electric power generator is a solid oxide fuelcell.

In one embodiment, the electric power generator comprises a commonexhaust conductor configured for receiving the hot exhaust.

In one embodiment, the at least one heat exchanger is adapted to receiveheat from a burner and output exhaust adapted to be emptied into thecommon exhaust conductor.

In one embodiment, the common exhaust conductor is a plastic duct.

In one embodiment, the output of the electric power generator isfunctionally connected to a local network.

An object of the present combined heat and power system is to provide acombined heat and power system capable of producing heat for localconsumption and electricity for local consumption and consumption ofcustomers within a local network such that reliance of the customers ofthe local network on public electrical grid can be reduced oreliminated.

Another object of the present combined heat and power system is toprovide a system capable of providing not only heat but alsoelectricity.

Another object of the present combined heat and power system is toprovide a system capable of utilizing waste heat from an electric powergenerator of the combined heat and power system in a water and/or spaceheating system of the combined heat and power system.

Whereas there may be many embodiments of the present invention, eachembodiment may meet one or more of the foregoing recited objects in anycombination. It is not intended that each embodiment will necessarilymeet each objective. Thus, having broadly outlined the more importantfeatures of the present invention in order that the detailed descriptionthereof may be better understood, and that the present contribution tothe art may be better appreciated, there are, of course, additionalfeatures of the present invention that will be described herein and willform a part of the subject matter of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above-recited and other advantagesand objects of the invention are obtained, a more particular descriptionof the invention briefly described above will be rendered by referenceto specific embodiments thereof which are illustrated in the appendeddrawings. Understanding that these drawings depict only typicalembodiments of the invention and are not therefore to be considered tobe limiting of its scope, the invention will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings in which:

FIG. 1 is one embodiment of a combined heat and power system accordingto the present invention.

FIG. 2 is one embodiment of a fluid heating and space heating systemconfigured for receiving heat from the heat recovery module of a microturbine.

FIG. 3 is a diagram depicting a combined heat and power system beingused by only one consumer.

FIG. 4 is a diagram depicting an arrangement where the electric powergenerated in a combined heat and power system is shared within a smallnetwork of consumers.

FIG. 5 is a diagram depicting a means by which the electric powergenerated in a combined heat and power system is shared within a smallnetwork of consumers.

FIG. 6 is a diagram depicting another means by which the electric powergenerated in a combined heat and power system is shared within a smallnetwork of consumers.

FIG. 7 is a diagram depicting an example of utilization of variouscomponents of a combined heat and power system throughout the time spanof a year.

PARTS LIST

2—combined heat and power system

4—heat recovery module of an electric power generator, e.g., microturbine

6—heat exchanger coil

8—electric power generator, e.g., micro turbine

10—hot exhaust of electric power generator, e.g., micro turbine

12—blower

14—ambient air

16—combined water and/or air heating system without burner

18—fluid heating system with burner

20—low temperature exhaust

22—common exhaust conductor

24—fluid input line

26—fluid output line

28—gas supply

30—plate-type heat exchanger

32—circulation pump

34—heat trap

36—bypass valve

38—flow sensor and control valve package

40—buffer tank

42—burner

44—supply line

46—return line

48—heat source

PARTICULAR ADVANTAGES OF THE INVENTION

The present combined heat and power system eliminates the need fordiscrete air and/or water heating systems and electric power generators.Combined heating systems and electric power generators enable waste heatfrom one system to be harnessed and utilized in another, therebyincreasing the total efficiency of the combined system. In occasionswhere such waste heat from the hot exhaust of the power generator cannotbe harnessed, the hot exhaust is diluted to yield tempered exhaust thatcan be carried using lower cost exhaust conductors, e.g., plastic ducts,as compared to stainless steel ducts suitable for carrying exhaust atsignificantly higher temperatures. As a result, equipment costs can bereduced significantly by using plastic ducts.

The present combined heat and power system supplies electric power tonearby consumers of a network of consumers via existing power lines thatare shared between the homes or points of use. No additional anddedicated power lines are necessary.

The losses due to transmission of electric power over short distances,e.g., several hundred feet is much less than the losses incurred due totransmission of power over long distances, e.g., miles to hundreds ofmiles. Therefore, when power is supplied by a source that is locatednearby, the transmission efficiency can be greatly increased.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The term “about” is used herein to mean approximately, roughly, around,or in the region of. When the term “about” is used in conjunction with anumerical range, it modifies that range by extending the boundariesabove and below the numerical values set forth. In general, the term“about” is used herein to modify a numerical value above and below thestated value by a variance of 20 percent up or down (higher or lower).

FIG. 1 is one embodiment of a combined heat and power system 2 accordingto the present invention. In this embodiment, the combined heat andpower system 2 includes an electric power generator 8, one or morecombined water and air/space heating systems or water heating systems. Aby-product of an electric power generator 8, hot exhaust 10 disposed ata temperature of from about 550 degrees F. to 2000 degrees F., ischanneled through one or more combined water and space heating systemsor one or more water heating systems. In the embodiment shown in FIG. 1,the hot exhaust generated in the electric power generator 8 is shownchanneled through two combined fluid and space heating systems 16, eachhaving a heat exchanger coil 6 configured for carrying water or anotherfluid, depending on the desired use of the fluid. For a residentialwater heating system, this fluid can be water. For a closed loop heatingsystem, e.g., a radiant floor heating system, this fluid can be ananti-freeze substance, e.g., Propylene Glycol. Each heat exchanger coil6 is connected to a fluid input line 24 for receiving a fluid to beheated and a fluid output line where heated fluid is sent. Each combinedfluid and space heating system further includes a blower 12 configuredto draw and merge ambient air 14 with the hot exhaust of the powergenerator such that the temperature of the hot exhaust 10 can be reducedto under about 220 degrees F. when heating is not demanded. The spentexhaust 20 from each combined fluid and space heating system isconfigured to empty into a common exhaust conductor 22. It can thereforebe recognized that a portion of the waste heat, e.g., up to as much asabout 75% of the waste heat, from an electric power generator 8 isrecovered and used in fluid heating. As the exhaust from the electricpower generator 8 has been tempered, the common exhaust conductor 22 canbe fabricated from low temperature components, e.g., plastic, instead ofcostly, high temperature grade materials, e.g., stainless steel. Thewater output line 26 of each combined water and space heating system issupplied to meet hot water and space heating requirements. In addition,there is shown several (e.g., four) additional hot water heating systems18, each having an independently provided heat source 48, e.g., aburner, electric heating element, etc., to supply heat to the water flowcarried in its heat exchanger coil 6. The exhaust 20 from each hot waterheating system 18 is also configured to empty into the common exhaustconductor 22. In the event no water and/or space heating is demanded butwhen the electric power generator continues to supply electricity orotherwise turned on, the blower 12 is turned on to reduce thetemperature of the hot exhaust from the electric power generator 8.

In one embodiment, the electric power generator 8 is a 15 to 20 kW microturbine. Reference is made to U.S. Pat. No. 6,198,174 entitling“Microturbine power generating system” to Nims et al. for a microturbine suitable for use in the present combined heat and power system.According to Wikipedia website, “Micro turbines are small-in-sizeelectricity generators that burn both gaseous and liquid fuels to createhigh-speed rotation, which turns an electrical generator.”

In another embodiment, the electric power generator 8 is a solid oxidefuel cell. Reference is made to U.S. Pat. No. 5,741,605 entitling “Solidoxide fuel cell generator with removable modular fuel cell stackconfigurations” to Gillett et al. for a solid oxide fuel cell suitablefor use in the present combined heat and power system. According toWikipedia website, “a solid oxide fuel cell (or SOFC) is anelectrochemical conversion device that produces electricity directlyfrom oxidizing a fuel. Fuel cells are characterized by their electrolytematerial; the SOFC has a solid oxide or ceramic, electrolyte. Advantagesof this class of fuel cells include high efficiency, long-termstability, fuel flexibility, low emissions, and relatively low cost. Thelargest disadvantage is the high operating temperature which results inlonger start-up times and mechanical and chemical compatibility issues”

FIG. 2 is one embodiment of a fluid (e.g., water) heating and spaceheating system configured for receiving heat from the heat recoverymodule 4 of a micro turbine. Cold water is drawn through the water inputline 24 and the water can receive heat through the heat exchanger coil 6from the burner 42 and/or the plate-type heat exchanger 30 which nowreceives a heat input from the hot exhaust of the heat recovery module 4of the micro turbine. Heated domestic water is delivered via the wateroutput line 26 to customers with or without the aid of circulation pump32. If recirculation is desired without a hot water demand, the pump 32must be turned on to recirculate water through the plate-type heatexchanger 30 and the buffer tank 40. In one example, the supply line 44transports a heated flow as a result of heat transfer from the hotexhaust from the heat recovery module 4 or the heat exchanger coil 6,out of the plate-type heat exchanger 30 to heat floors in radiant floorheating or baseboards and air coils in baseboard heating and returns theflow via the return line 46. Heat trap 34 prevents excessively hot fluidof the water heating system from reaching the fluid output line 26 asthe fluid exiting the fluid output line 26 may come in direct contactwith a human consumer. A bypass valve 36 is made available should mixingof incoming unheated fluid through the fluid input line 24 and theheated fluid through the fluid output line 26 is desired. The flowsensor and control valve package 38 provides the fluid heating and spaceheating system the incoming unheated flowrate, such that its controlvalve may be adjusted to control the flowrate of unheated flowrate intothe heating system.

FIG. 3 is a diagram depicting a combined heat and power system beingused by only one consumer. In addition to water and space heating,electric power is provided. If a micro turbine is used, the only supplyrequired by the combined heat and power system is a fuel supply 28,e.g., propane, natural gas, etc. The generated electric power may beconsumed entirely within a home but excess power is typically availabledue the amount of power generated from a power generator having capacitylarge enough to be economically feasible to own and operate. The excesspower is configured to be put on the municipal/public electrical grid orsimply public electrical grid such that it may be used by neighboringconsumers. If a public electrical grid is unavailable, a privateelectrical grid connecting only a local network of consumers may becreated. The geographical reach of a private electrical grid may rangefrom several hundred feet to tens of thousands of feet. If a publicelectrical grid is available and that a local network of consumers arelocated in close vicinity, e.g., within distances of from severalhundreds of feet to tens of thousands of feet from where the electricpower is generated, the local electric power generator may serve as anelectric provider to these consumers. In the event the local network ofconsumers are served via a public electrical grid, the voltage level ofthe locally generated electric power transmission is boosted by athreshold of from about 5 V to about 30 V above the voltage at which thepublic electrical grid is disposed and transmitted in phase with thepublic electrical grid. As such, the local network of consumers drawpower from the local producer and not from the large-scale powerproviders located at great distances, e.g., miles to hundreds of miles.As transmission losses over short distances are negligible compared totransmission losses over great distances, the ability to generate andtransmit power locally reduces wastes and lowers the cost of deliveredpower.

FIG. 4 is a diagram depicting an arrangement where the electric powergenerated in a combined heat and power system is shared within a smallnetwork of consumers. It shall be noted that the generated heat isconsumed within the home to which the combined heat and power system isdisposed. Excess electric power is put on a public electrical grid suchthat it can be transmitted to and consumed in neighboring homes. In oneexample, the amount of compensation each consumer makes to a localsupplier of electric power may be based on the consumer's historicalelectric power usage drawn from the public electrical grid, prior to theimplementation of such a local supply of electric power. The consumermay simply pay a flat fee to the local supplier.

In one embodiment, further economic benefits may be realized when eachconsumer participating in a lower power distribution scheme is capableof scheduling its power usage based on the most favorable energy pricingor availability of locally generated electric power at a particular timeof day. For instance, if at peak power production, a total of twentyappliances, e.g., Internet of Things (commonly known as IOT) devicesacross the local network of consumers may be turned on at the same timedue to power generating limitations of the local combined heat and powersystem, a request to turn on an additional appliance using the locallyprovided electric power may be declined. The request may be scheduled tobe met at a later time when the operations of other appliances haveconcluded. Reference is made to Applicants' co-pending application U.S.Pat. Pub. No. 2012/0191256 entitling “Masterless control system methodsfor networked water heaters” for a mechanism useful for controllingappliances over a network of consumers. Appropriate parameters of thenetwork, e.g., usage of a water heating system, may be manipulated toprevent or allow the activation of the water heating system. FIG. 5 is adiagram depicting a means by which the electric power generated in acombined heat and power system is shared within a small network ofconsumers. The electric power-consuming devices or appliances availablein each home are functionally connected to a network, e.g., via a cloudsolution, where each device is properly identified and capable to bescheduled to start functioning at any moment.

FIG. 6 is a diagram depicting another means by which the electric powergenerated in a combined heat and power system is shared within a smallnetwork of consumers. The potential of the combined heat and powersystem is raised to a value matching the level of the public electricalgrid. Note that the output from the combined heat and power system isconnected to a public electrical grid at a point upstream of aneighborhood transformer.

FIG. 7 is a diagram depicting an example of utilization of variouscomponents of the present combined heat and power system throughout thetime span of a year. The primary home at which the combined heat andpower system is disposed consumes all the heat by-product to heat waterand space. The thick solid line represents the unit of energy thecombined heat and power or the public electrical grid start out with.The dash line represents the energy losses due to electric transmissionover great distances. The line dotted with square boxes representsenergy losses due to the generation of waste heat from the electricpower generator over warm months as the waste heat rejected from theelectric power generator is not used in heating. It shall be noted fromthe diagram that even with the heat from the combined heat and powersystem that is not used, the amount of losses of the combined heat andpower system is less than that of the grid losses as all of the heatgenerated as a by-product of electric power production is used duringcold months. It shall be noted that the difference between the dash lineand the line dotted with square boxes represents the heat generated as aby-product of electric power production that is utilized in the combinedwater and space heating system.

The detailed description refers to the accompanying drawings that show,by way of illustration, specific aspects and embodiments in which thepresent disclosed embodiments may be practiced. These embodiments aredescribed in sufficient detail to enable those skilled in the art topractice aspects of the present invention. Other embodiments may beutilized, and changes may be made without departing from the scope ofthe disclosed embodiments. The various embodiments can be combined withone or more other embodiments to form new embodiments. The detaileddescription is, therefore, not to be taken in a limiting sense, and thescope of the present invention is defined only by the appended claims,with the full scope of equivalents to which they may be entitled. Itwill be appreciated by those of ordinary skill in the art that anyarrangement that is calculated to achieve the same purpose may besubstituted for the specific embodiments shown. This application isintended to cover any adaptations or variations of embodiments of thepresent invention. It is to be understood that the above description isintended to be illustrative, and not restrictive, and that thephraseology or terminology employed herein is for the purpose ofdescription and not of limitation. Combinations of the above embodimentsand other embodiments will be apparent to those of skill in the art uponstudying the above description. The scope of the present disclosedembodiments includes any other applications in which embodiments of theabove structures and fabrication methods are used. The scope of theembodiments should be determined with reference to the appended claims,along with the full scope of equivalents to which such claims areentitled.

What is claimed herein is:
 1. A combined heat and power systemcomprising: (a) an electric power generator configured to receivegaseous fuel and output hot exhaust and electricity at a voltage level;(b) at least one heat exchanger comprising a fluid input line, a fluidoutput line and a heat exchanger coil connecting said fluid input lineand said fluid output line and adapted to prepare a hot fluid, whereinsaid at least one heat exchanger is thermally adapted to the hotexhaust; and (c) a blower configured for selectively drawing ambient airto be mixed with the hot exhaust, whereby when the hot fluid isdemanded, said blower is not enabled and a fluid is drawn through saidfluid input line and delivered at said fluid output line to cause heatrecovery from the hot exhaust to the fluid and when the hot fluid is notdemanded, said blower is turned on to draw ambient air that is mixedwith the hot exhaust such that the temperature of the hot exhaust can bereduced.
 2. The combined heat and power system of claim 1, wherein saidvoltage level is disposed at a level of from about 5 V to about 30 Vhigher than the supply voltage of a public electrical grid such thatelectricity generated of said electric power generator may betransmitted via the public electrical grid.
 3. The combined heat andpower system of claim 1, wherein said electric power generator is amicro turbine.
 4. The combined heat and power system of claim 1, whereinsaid electric power generator is a solid oxide fuel cell.
 5. Thecombined heat and power system of claim 1, wherein said electric powergenerator comprises a common exhaust conductor configured for receivingthe hot exhaust.
 6. The combined heat and power system of claim 5,wherein said at least one heat exchanger is adapted to receive heat froma burner and output exhaust adapted to be emptied into said commonexhaust conductor.
 7. The combined heat and power system of claim 5,wherein said common exhaust conductor is a plastic duct.
 8. The combinedheat and power system of claim 1, wherein said fluid is water.
 9. Thecombined heat and power system of claim 1, wherein the output of saidelectric power generator is functionally connected to a local network.10. A combined heat and power system comprising: (a) an electric powergenerator configured to receive gaseous fuel and output hot exhaust andelectricity at a voltage level disposed at a level of from about 5 V toabout 30 V higher than the supply voltage of a public electrical gridsuch that electricity generated of said electric power generator may betransmitted via the public electrical grid; (b) at least one heatexchanger comprising a fluid input line, a fluid output line and a heatexchanger coil connecting said fluid input line and said fluid outputline and adapted to prepare a hot fluid, wherein said at least one heatexchanger is thermally adapted to the hot exhaust; and (c) a blowerconfigured for selectively drawing ambient air to be mixed with the hotexhaust, whereby when the hot fluid is demanded, said blower is notenabled and a fluid is drawn through said fluid input line and deliveredat said fluid output line to cause heat recovery from the hot exhaust tothe fluid and when the hot fluid is not demanded, said blower is turnedon to draw ambient air that is mixed with the hot exhaust such that thetemperature of the hot exhaust can be reduced.
 11. The combined heat andpower system of claim 10, wherein said electric power generator is adevice selected from the group consisting of a micro turbine and a solidoxide fuel cell.
 12. The combined heat and power system of claim 10,wherein said electric power generator comprises a common exhaustconductor configured for receiving the hot exhaust.
 13. The combinedheat and power system of claim 12, wherein said at least one heatexchanger is adapted to receive heat from a burner and output exhaustadapted to be emptied into said common exhaust conductor.
 14. Thecombined heat and power system of claim 12, wherein said common exhaustconductor is a plastic duct.
 15. The combined heat and power system ofclaim 10, wherein said fluid is water.
 16. A combined heat and powersystem comprising: (a) an electric power generator configured to receivegaseous fuel and output hot exhaust and electricity at a voltage level;(b) at least one heat exchanger comprising a water input line, a wateroutput line and a heat exchanger coil connecting said water input lineand said water output line adapted to prepare a hot water supply,wherein said at least one heat exchanger is thermally adapted to the hotexhaust; and (c) a blower configured for selectively drawing ambient airto be mixed with the hot exhaust, whereby when the hot water supply isdemanded, said blower is not enabled and a water flow is drawn throughsaid water input line and delivered at said water output line to causeheat recovery from the hot exhaust to the water flow and when the hotwater supply is not demanded, said blower is turned on to draw ambientair that is mixed with the hot exhaust such that the temperature of thehot exhaust can be reduced.
 17. The combined heat and power system ofclaim 16, wherein said voltage level is disposed at a level of fromabout 5 V to about 30 V higher than the supply voltage of a publicelectrical grid such that electricity generated of said electric powergenerator may be transmitted via the public electrical grid.
 18. Thecombined heat and power system of claim 16, wherein said electric powergenerator is a device selected from the group consisting of a microturbine and a solid oxide fuel cell.
 19. The combined heat and powersystem of claim 16, wherein said electric power generator comprises acommon exhaust conductor configured for receiving the hot exhaust. 20.The combined heat and power system of claim 19, wherein said commonexhaust conductor is a plastic duct.